The field of the present invention is the structural architecture and arrangement of motorcycles.
Conventional motorcycles have typically employed a frame structure within which a power unit, comprising an engine and transmission, is mounted. A rear swing arm suspension is typically employed on such vehicles and a telescopic front fork mechanism pivotally mounted to a head tube on the frame is employed for the front suspension thereof.
Motorcycle architecture has, from time to time, been changed to accomplish certain specific design requirements. To reduce weight and lower the center of gravity of such a vehicle, an arrangement has been known which eliminates the front fork mechanism and replaces it with a swing arm suspension mechanism. One such device is illustrated in Japanese Patent Publication No. 58,49435, U.S. Pat. No. 4,265,329. This prior device employs front and rear swing arms mounted to the engine which provides the frame structure of the vehicle. A tripod arrangement is employed to mount the handlebar assembly directly to the frame structure defined by the vehicle power unit. This arrangement has been found to be very light with a low center of gravity due to the simplified body frame.
In spite of the foregoing advantages, such a vehicle has found disadvantage in the elimination of the frame. Motorcycle equipment necessary for the operation of the vehicle, such as the handlebar, a seat, a fuel tank and lights have been individually mounted on the frame structure. Thus, to work on the power unit, or to otherwise initially assemble the vehicle, extensive labor is required to remove the several separately mounted pieces of equipment. Furthermore, an arrangement employing the power unit as the entire frame structure sacrifices flexibility in the mounting of the suspension systems, likely to require heavy plate members, and in the location of components such that space may be optimized without detracting from any equipment component.